Ptyonoprogne rupestris, commonly known as the Eurasian crag martin or andorinha-das-rochas, is a small passerine bird belonging to the Hirundinidae family, which includes swallows and martins. The species occurs across southern Europe, North Africa and large parts of Asia.
Unlike many other swallows, the crag martin is often associated with mountainous or rocky environments and is capable of remaining in parts of Europe throughout the year.
The Eurasian crag martin prefers rocky cliffs, escarpments and mountainous areas, where it can nest in protected ledges or cavities.
In Portugal, the species occurs from north to south and may also use bridges, buildings or other human structures as nesting sites when natural cliffs are unavailable.
In landscapes such as Vale do Lourêdo, rocky slopes, stone walls and nearby cliffs provide suitable environments for this species.
The Eurasian crag martin measures approximately 13 to 15 cm in length and has a wingspan of around 32 to 34 cm.
Its plumage is mainly ash-brown on the upperparts with paler underparts, and the tail is short and square. A distinctive feature is the presence of white patches on the tail feathers, visible when the bird spreads its tail in flight.
Both sexes look similar, although juveniles tend to have slightly paler feather edges.
Like most swallows, the Eurasian crag martin feeds on flying insects, catching them in the air while performing agile flight manoeuvres near cliffs or open spaces.
Its flight is slightly slower and more gliding than that of other swallows, often alternating rapid wingbeats with short glides.
The nest is usually built with mud and plant material, attached to rock surfaces or structures under overhangs.
As an insect-eating bird, the Eurasian crag martin contributes to the natural regulation of flying insect populations.
Its presence in landscapes such as Vale do Lourêdo reflects the availability of rocky habitats and open aerial feeding areas, which support diverse bird communities.